The problem of trash disposal has become increasingly important in recent years; economizing on packaging materials, such as boxes, foils, paper bags, and the like, which as a rule are used only once, has been recommended. Cardboard boxes, which in principle could be used several times, are basically discarded, because of the relatively high cost of return shipment and because of the danger of possible damage after the single use. The costs of disposal for industrial and commercial trash are rising rapidly.
There is accordingly a need for practical, repeatedly usable package that on the one hand is sufficiently stable and wearproof and on the other can be used so universally that it can replace the boxes currently used for many purposes. This is true typically for the textile industry, for instance, in which yarn packages in large quantities were previously shipped from yarn manufacturers to the yarn-processing facilities in cardboard boxes that were intended for only a single use; shipping them back again for re-use is not considered worthwhile, if for no other reason than the considerable amount of space they occupy.
Especially from the transcontainer industry, constructions for collapsible or foldable containers have become known, which can be changed from an erected position for use into a flat position for being shipped empty, in which latter position the space required for empty or return shipping is substantially reduced.
These transcontainers, whose dimensions and basic structural elements are standardized, are as a rule made of sheet steel. They are arranged so as to be moved with special hoisting tools, and their special embodiment is also dependent on the goods to be shipped.
In this kind of large-volume transcontainer or container, known from German Patent Disclosure Document DE-OS 33 17 221, the end and side walls are joined rotatably to a flat, pallet-like bottom element by hinges, so that after the top element is removed, they can be folded down onto the bottom element to put the container in the flat, empty shipping position. The top element is placed on the wall parts, which are folded flat down on one another, and firmly joined to them by bolts and straps. Because of the relatively great weight of the wall parts and top element, folding in of the wall part can be done only with the aid of hoisting tools, and the correct placement of the top element, such that the bolts used for fastening enter their proper holes, requires considerable care and skill on the part of workers. Moreover, the axes of the hinges of the various wall elements must be at a variable distance from the bottom face of the bottom element, to enable folding up its wall parts so that they lie flat. Aside from the fact that this can entail difficulties in terms of construction, a predetermined order in the folding process must also be adhered to, which once again means that trained workers are a precondition if damage to the hinges or wall parts is to be prevented.
In principle, the same comments apply to a collapsible transcontainer known from Canadian Patent 875,957, in which the opposed end walls are embodied as hinged doors, which to be folded down to the empty shipping position can be folded about their vertical hinge axes onto the outside of the associated side wall, so that they lie flat. In this transcontainer, special seals between the side walls and the top and bottom elements and the doors are additionally provided, in order to assure that the container interior is sealed off at least from splashing water.
In another collapsible cargo container according to ISO Standards, known from German Patent Disclosure Document DE-OS 38 05 981, each side wall is made up of three sections, joined together by hinges, while the end walls on the container are supported movably in such a way that they can be moved out of the normal closing position into a position in which they can be slipped under the top of the container. To collapse the container, the side wall sections are folded inward about their hinge axes in accordion-like fashion, so that in the empty shipping position, the top part, the end walls, the middle and bottom sections of the side walls and the bottom element rest on one another in layered fashion. The container can be folded down can be done only by means of a hoisting tool that engages the corner sockets of the top part, and in view of the danger of accidents, considerable care must be taken.
It is also known from German Utility Model DE-GM 86 11 553, in a transcontainer in which the end and side walls are joined to the bottom element by hinges, to form the top element in two parts as well and connect it to the side walls by hinges. Doors provided in the end walls are formed such that in the process of collapsing the container, they can be folded outward, flat on one another. In this transcontainer, a tubular frame with coating sheets is used; the wall parts, in the erected position for use, are locked together with lever closures. The many hinge axes of these transcontainers impair their stability in the erected state and make satisfactory sealing of the container interior appear possible only with difficulty. Aside from that, it is difficult and inconvenient to manipulate this transcontainer in the process of collapsing it.
Finally, a cargo container for small loads or the like, constructed in lightweight fashion, is known from German Patent Disclosure Document DE-OS 30 24 707; the invention is based on this container, in which the use of hinges as connection means between the bottom and top elements and the side wall elements is dispensed with. Both the bottom and top elements and the side wall elements here comprise aluminum sectional frames and thin aluminum panels joined to them, which are optionally provided with beads or integrally molded reinforcement ribs. The bottom element and the top element are joined together in spaced-apart fashion by vertical pillars on which the intrinsically stable side walls are fixed; the pillars on the bottom element and on the top element are detachably connected by means of cuboid corner parts that have protrusions that protrude into hollow spaces in the corner pillars, which are embodied as hollow profile sections. Additional fastening screws keep these plug-in connectors, located at the corners of the bottom and top elements, together.
Assembling and disassembling the cargo container as needed, to put it in the erected position for use or the flat position for being shipped empty, involves relatively many separate parts. Aside from the fact that this makes the process of assembly and disassembly itself relatively time-consuming and inconvenient, special precautions must also be taken so that the loose individual parts will not be lost during the empty shipment.